In a known structure, a sub-frame, a lower arm (lateral link), and a tension rod are disposed below a front portion of a front sub-frame structure to form a triangular shape in plan view, and thus, an engine is mounted in a rear portion of the front sub-frame structure where the lower arm and the tension rod, for example, are not disposed.
On the other hand, in many known structures, the rear portion of the front sub-frame has a frame structure that is constituted by a cross member coupled to left and right arm supporting parts and left and right side members extending rearward and has a rectangular shape in plan view that is open to the rear.
In the frame structure having such a rectangular shape in plan view in which one longitudinal side (one side in the front-rear direction) of the front sub-frame is open to this side, in a case where the engine is mounted at this side, engine support stiffness and lower arm support stiffness might decrease. In such a case, there arises a problem of inferior operation responsiveness in operating a steering wheel.
On the other hand, as exemplified by Patent Document 1 listed below, a sub-frame in which an X-shaped brace (3) formed by crossing a pair of beams in plan view is disposed in a rear portion of a front sub-frame to thereby reinforce the rear portion is proposed. Patent Document 2 describes a pair of tilt members that has longitudinal ends coupled to a cross member (1d) and left and right side members (1b), extends rearward, and tilts outward in the lateral direction (vehicle width direction or left-right direction) in such a manner that the distance between the tilt members in the vehicle width direction increases toward the rear in plan view.